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QoS for subnet

I have an ASA 5505, with 2x internet vlans and 2x internal VLANS (one for data and one for voice).. I would like a simple QoS policy to ensure that voice is always given priorty over data, this includes when travelling through the ASA and out each internet interface.

Thanks in advance..

1 REPLY

Re: QoS for subnet

Hello,

You can apply the QOS on the global policy, so it will be attache to all the ASA interfaces when it detects this is voice traffic.

1- Create a low latency queue for the traffic:

hostname(config) priority-queue outside

hostname(config-priority-queue) queue-limit 256

hostname(config-priority-queue) tx-ring-limit 3

hostname(config) priority-queue outside2

hostname(config-priority-queue) queue-limit 256

hostname(config-priority-queue) tx-ring-limit 3

2- Select the traffic that you will need to give priority, ( like the access-list that you have on the Router)

access-list qos_voice permit tcp any any eq SIP

access-list qos_voice permit udp any any eq SIP

*If they are Cisco Phones SIP can use tcp or udp, by default voice packets

will have the DSCP value of EF. Therefore, you can use a matching criteria

like the following:

hostname(config)# class-map VOICE

hostname(config-cmap)# match dscp ef

3- Create a class map with the traffic

hostname(config) class-map qos_voice

hostname(config-cmap) match access-list qos_voice

4- Set priority to that class-map on the gloval_policy

hostname(config) policy-map global_policy

hostname(config-pmap) class qos_voice

hostname(config-pmap-c) priority

Regards,

Do rate helpful posts!

Julio

Julio Carvajal
Senior Network Security and Core Specialist
CCIE #42930, 2xCCNP, JNCIP-SEC
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